Orf: reasons to take an interest in control

ORF, also known as contagious pustular dermatitis (CPD), is a highly contagious viral disease, primarily of sheep and goats, that is widespread in those parts of the world where small ruminants are kept. The disease is caused by a parapox virus and is a frequently recognised zoonosis among people working with infected stock. Affected animals develop scabs that can become very extensive and develop into proliferative wart virus lesions.

The aetiology, clinical signs, pathology, diagnosis and epidemiology and control are well described in the literature (Reid and Rodger 2007, Sargison 2008). To summarise, orf is recognised as a production-limiting disease of sheep. Clinical disease is typically seen in three categories of animals: lactating ewes, suckling lambs and lambs after weaning.

In ewes, lesions are usually found on the udder and teats, and acute bacterial mastitis is often a sequel. Orf in young suckling lambs is usually confined to the mouth and nostrils (Fig 1), but sometimes will extend further into the mouth and throat. Disease in lambs is often concurrent with disease in ewes. The third category affected by outbreaks of orf is lambs after weaning, where again the virus results in pustules over the face. Lambs on rough grazing with thistles, nettles and gorse are particularly prone to these outbreaks due to abrasions to, or breaks in, the skin. Less commonly recognised forms of orf include venereal lesions …